Gear machine having a non-circular low-pressure connection

Abstract

A gear machine includes two externally intermeshing gear wheels enclosed by a housing that has a high-pressure connection and a low-pressure connection situated opposite one another. On an inner circumferential face of the housing, a notional boundary line is assigned to both gear wheels. The line runs parallel to the line of contact between the gear tooth tips of the gear wheels and the inner circumferential face. The intersection edge is located between the two boundary lines and the minimum distance between the intersection edge and the boundary lines are at least one pitch interval of the gear wheels. The cross sectional shape of the low-pressure connection deviates from the circular shape such that its cross sectional area overlapping the gear wheels is greater than the cross sectional area of a notional, circular low-pressure connection overlapping the gear wheels at the same minimum distance from the boundary lines.

What is claimed is: 
     
       1. A gear machine, comprising:
 a housing having a high-pressure connection, a low-pressure connection, a central axis extending through the high-pressure connection and the low-pressure connection, and an inner circumferential face, the low-pressure connection having a constant cross sectional shape in a direction of the central axis, an intersection edge formed where the low-pressure connection intersects the inner circumferential face; 
 two externally intermeshing gear wheels each including gear tooth tips and at least one lateral face, the gear wheels arranged within the housing such that the inner circumferential face bears tightly against the gear tooth tips, the gear wheels arranged such that the high-pressure connection and the low-pressure connection are situated on opposite sides of the gear wheels; and 
 at least one bearing liner arranged on both sides of each of the gear wheels so as to bear tightly on the at least one lateral faces of the gear wheels, the at least one bearing liner configured to rotatably support each of the gear wheels, the at least one bearing liner having at least one pressure equalization chamfer assigned to each of the gear wheels, the at least one pressure equalization chamfer having an end, the at least one pressure equalization chamfer extending opposite the at least one lateral face of a respective gear wheel and opposite the inner circumferential face, the at least one pressure equalization chamfer extending in a direction from the high-pressure connection toward the low-pressure connection to the end of the at least one pressure equalization chamfer, 
 
       wherein:
 a notional boundary line is assigned to each of the gear wheels, each notional boundary line defined on the inner circumferential face so as to intersect with the end of the at least one pressure equalization chamfer, 
 a line of contact is assigned to each of the gear wheels, each line of contact defined where the gear tooth tips of the respective gear wheel contact the inner circumferential face, 
 each notional boundary line is parallel to the line of contact of the respective gear wheel, 
 the intersection edge is located between the notional boundary lines, 
 a minimum distance between the intersection edge of the low-pressure connection and each of the notional boundary lines is equal to or greater than at least one pitch interval of the gear wheels, 
 the cross sectional shape of the low-pressure connection defines a cross sectional area where the cross sectional shape overlaps with the gear wheels in the direction of the central axis, 
 a notional low-pressure connection has a circular cross sectional shape defined at the minimum distances from the notional boundary lines, the circular cross sectional shape defines a notional cross sectional area where the circular cross sectional shape overlaps with the gear wheels in the direction of the central axis, and 
 the cross sectional shape of the low-pressure connection differs from the circular cross sectional shape such that the cross sectional area is greater than the notional cross sectional area. 
 
     
     
       2. The gear machine according to  claim 1 , wherein the cross sectional shape of the low-pressure connection is formed so that the intersection edge is at a constant distance from each of the notional boundary lines. 
     
     
       3. The gear machine according to  claim 1 , wherein the cross sectional shape of the low-pressure connection comprises two first straight lines, each of the first straight lines arranged nearly parallel to an associated notional boundary line. 
     
     
       4. The gear machine according to  claim 3 , wherein the two first straight lines are connected by at least one second straight line, the at least one second straight line runs in alignment with the at least one lateral faces of the gear wheels. 
     
     
       5. The gear machine according to  claim 4 , wherein the two first straight lines are connected by two second straight lines, the second straight lines run in alignment with the lateral faces of the gear wheels. 
     
     
       6. The gear machine according to  claim 3 , wherein the two first straight lines are connected to one another by at least one circular arc. 
     
     
       7. The gear machine according to  claim 6 , wherein the two first straight lines are connected to one another by two circular arcs. 
     
     
       8. The gear machine according to  claim 1 , wherein the cross sectional shape of the low-pressure connection has rounded corners. 
     
     
       9. The gear machine according to  claim 1 , wherein the cross sectional shape of the low-pressure connection is formed by more than one circle, the circles having centers offset in relation to one another. 
     
     
       10. The gear machine according to  claim 9 , wherein the cross sectional shape of the low pressure connection is formed by two overlapping circles, which have centers offset in relation to one another. 
     
     
       11. The gear machine according to  claim 1 , wherein the low-pressure connection overlaps the at least one bearing liner. 
     
     
       12. The gear machine according to  claim 1 , wherein the gear machine is configured as a pump or a motor. 
     
     
       13. The gear machine according to  claim 1 , wherein the two externally intermeshing gear wheels are helical toothed gear wheels. 
     
     
       14. The gear machine according to  claim 1 , wherein:
 the inner circumferential face bears tightly against the gear tooth tips along a portion of the inner circumferential face; and 
 the intersection edge intersects with the portion of the inner circumferential face.